This invention relates to apparatus for locking and holding a nuclear fuel assembly and more particularly to apparatus for locking and holding a nuclear fuel assembly while the fuel rods are removed from the fuel assembly.
After a period of operation of a nuclear reactor, the fuel assemblies comprising the core of the nuclear reactor must be rearranged with the depleted or spent fuel assemblies being replaced with fresh ones. The spent fuel assemblies are removed from the reactor vessel and generally stored in a pool of water on the reactor site. Since a conventional fuel assembly comprises structure other than fuel rods such as grids and control rod guide tubes, a spent fuel assembly occupies more space in the storage pool than would be required for the individual fuel rods. Because the storage pool has a finite volume it would be desirable to be able to store the fuel rods in a closely packed array and with a minimum of support structure to thereby maximize the amount of spent nuclear fuel that can be stored in a given volume of the storage pool. This would provide a greater storage capacity for the spent fuel rods until the fuel rods are transported off the reactor site for storage or reprocessing.
However, since the spent fuel rods have been irradiated during reactor operation, they are highly radioactive and can be handled only by remote manipulators and while the fuel rods are submerged in a coolant. The radioactive nature of the spent fuel assemblies increases the difficulty of not only transporting the spent fuel assembly but of also dismantling the fuel assembly and storing the spent fuel rods.
In order to dismantle or disassemble an irradiated fuel assembly so that the spent fuel rods may be removed from the fuel assembly without damaging the fuel rods, it may be necessary to secure or hold the fuel assembly while the fuel rods are removed. Since the dismantling is performed under water, the fuel assembly must be secured positively and remotely and must, likewise, be able to be released remotely.
Therefore, what is needed is apparatus for remotely and positively securing a fuel assembly under water while the fuel rods are removed therefrom without damaging the fuel assembly or the fuel rods.